Microelectromechanical systems (MEMS) devices (e.g., acceleration sensors) may be mass products of automotive and consumer durable electronics. Among others things, systems are desired which integrate a simple threshold switch into an ASIC (application-specific integrated circuit). Such a system is used e.g., in TPMS (tire-pressure monitoring system) sensors.
In the migration into more recent technology nodes, there is the challenge of integrating these systems such that the complexity of a complementary metal-oxide-semiconductor (CMOS) process is not unnecessarily augmented and that the existing integration scheme of the CMOS circuit can be largely maintained with as little development expenditure as possible.
In technologies involving structural widths of, for example, 130 nm and below, the topology of the front-end-of-line structures, for example, plays an important part. They should not exceed an overall thickness of several hundred nanometers so as not to negatively affect the borophosphosilicate glass (BPSG) polishing step, which is often performed.
In addition, reduction to as few additional steps as possible and joint utilization of existing processes are pre-requisites for successful integration.
Besides the CMOS compatibility, it is also desirable to form the MEMS devices with a decreasing frame size without reducing the sensitivity of the sensors.